KR100402838B1 - Polyester multifilament yarns - Google Patents

Abstract

The present invention relates to a polyester multifilament yarn, comprising the steps of (A) melt spinning a solid-state polymerized polyester chip having an intrinsic viscosity in the range of 1.05 to 1.13 at a temperature of 2790 to 298 ° C., (B) melting Quenching the discharged yarn through a cooling zone, (C) winding the yarn at a spinning speed such that the birefringence of the undrawn yarn is 0.06 to 0.09 and the density is 1.360 to 1.375, and (D) wound Stretched polyester multifilament yarns having a final single yarn fineness of 2.5 to 3.5 denier having a high modulus and a low shrinkage, prepared according to a method comprising hot drawing the yarn to a total draw ratio of 1.5 to 2.5, wherein the treated cord formed therefrom It has excellent dimensional stability and strength and is usefully used as a reinforcement material for rubber products.

Description

Polyester multifilament yarn {POLYESTER MULTIFILAMENT YARNS}

The present invention relates to an improved polyester multifilament yarn having high modulus and low shrinkage, which is particularly useful as a fiber reinforcement of a tire, wherein the yarn of the present invention has excellent dimensional stability and tenacity. Provides a treated cord with

Polyester fiber is one of the widely used fibers, and high strength polyester fiber is widely used in a variety of industrial applications including rubber cord reinforcement tire cords, seat belts, conveyor belts, V-belts and hoses. It is being used, especially when converted to a treatment cord through latex treatment and heat treatment to apply as a fiber reinforcement of rubber tires, excellent dimensional stability and strength is required.

US Pat. No. 4,101,525 (Davis et al.) And US Pat. No. 4,491,657 (Cyto et al.) Disclose industrial polyester multifilament yarns having high initial modulus and low shrinkage. However, it is known that the yarns disclosed in these patents do not satisfy the characteristics required as tire cords due to a decrease in strength when converted into treatment cords.

Therefore, as a method of increasing the strength of multifilament polyester fibers, US Patent No. 4,690,866 proposes a method of spinning using polyester chips having a high intrinsic viscosity (I.V.) of 1.2 or more. Increasing the viscosity of the chip increases the orientation of the unstretched yarn and increases the formation of a tie chain that connects the crystal to the crystal, thereby exhibiting excellent strength when converted to the treatment cord. However, the high intrinsic viscosity used in this method is very different from the intrinsic viscosity of the surface and the central part during solid state polymerization, so when melt spinning, the radioactivity is lowered due to the viscosity unevenness and filament cut is generated, resulting in fairness and appearance. In addition to being poor, since the thermal radiation and hydrolysis occurs due to the melt spinning at a high temperature, the fibers that are actually spun have a problem that does not have a high viscosity as the chip has.

Accordingly, it is an object of the present invention to provide a polyester multifilament yarn having improved physical properties capable of producing tire cords with excellent dimensional stability and strength.

1 is a schematic diagram of a polyester multifilament yarn manufacturing process according to one embodiment of the present invention.

<Short description of drawing symbols>

1: pack 2: nozzle

3: cooling zone 4: emitting yarn

L: Hood Length 5: Emulsion Device

6, 7, 8, 9, and 10: stretching roller 11: final stretched yarn (yarn)

In the present invention to achieve the above object,

(A) obtaining a discharge yarn by melt spinning a solid-phase polymerized polyester chip containing at least 90 mol% of ethylene terephthalate units and having an intrinsic viscosity in the range of 1.05 to 1.13 at a temperature of 290 to 298 ° C.,

(B) quenching the molten yarn through a cooling zone;

(C) winding the yarn at a spinning speed such that the birefringence of the undrawn yarn is 0.06 to 0.09 and the density is 1.360 to 1.375, and

(D) provides a polyester multifilament yarn having the following physical properties, prepared by a method comprising the step of hot stretching a wound yarn at a total draw ratio of 1.5 to 2.5;

(1) single thread fineness of 2.5 to 3.5 denier, (2) intrinsic viscosity of 0.94 to 1.00, (3) DEG (diethylene glycol) content of 0.65 to 0.9 wt%, (4) 23 wt% or less of CEG (carboxyl) Endgroup) content, (5) strength of 7.5 to 8.5 g / d, (6) elongation of 13.0 to 16.0%, (7) shrinkage of 4.0 to 7.0%, and (8) silk factor of 27 or more (strength (g / d) x √ Elongation at break (%)).

Hereinafter, the present invention will be described in more detail.

The polyester chip used in the present invention contains at least 90 mol% of ethylene terephthalate units and preferably consists only of ethylene terephthalate units. The polyester chip may also comprise small amounts of units derived from one or more diols or dicarboxylic acids, rather than ethylene glycol and terephthalic acid or derivatives thereof as copolymer units.

The polyester chip according to the present invention, by adding an antimony compound as a main polymerization catalyst and melt polymerizing the raw materials to make a low viscosity raw chip (low chip) to have an intrinsic viscosity of 1.05 to 1.13 and a moisture content of 30 ppm or less under vacuum Solid phase polymerization If the intrinsic viscosity of the chip is lower than 1.05, the intrinsic viscosity of the final drawn yarn is lowered, so that it is impossible to exhibit high strength as a treatment cord after heat treatment. If the intrinsic viscosity of the chip is higher than 1.13, the radial tension is excessively increased and the cross section of the emitter is uneven, thus stretching Many filament cuts generate | occur | produce and drawability worsens. If the moisture content of the chip exceeds 30ppm, hydrolysis occurs during melt spinning. In addition, the antimony compound used as a polymerization catalyst in the production of the polyester polymer may be added in an amount such that the amount remaining as the antimony metal in the polyester polymer is 200 to 300 ppm (the addition method is not particularly limited). If less than 200ppm, the polymerization reaction rate is slowed to decrease the polymerization efficiency. If it is more than 300ppm, the workability is poor, such as the pack pressure is increased by the precipitation of the catalyst after polymerization and the nozzle contamination rate is increased.

The production method of the polyester multifilament yarn according to the present invention is melt-extruded by melt extrusion at a lower temperature without excessively increasing the intrinsic viscosity of the polyester polymer by using a raw material which has characteristics of a typical polyester polymer for tire cords. The technical characteristics include minimizing the decrease in intrinsic viscosity of the polymer during the process and lowering the single yarn fineness of the final stretched yarn to increase the cooling effect of the emitter, and optimizing the spinning speed to make and stretch the undrawn yarn with an appropriate level of birefringence. do.

1 schematically shows a manufacturing process according to one embodiment of this invention.

In step (A), the polyester chip is melt-melted at a temperature of 290 to 298 ° C. through the pack 1 and the nozzle 2 to prevent the lowering of the viscosity of the polymer by pyrolysis and hydrolysis. At this time, the fineness of the emitting yarn is adjusted so that the single yarn fineness of the final stretched yarn is 2.5 to 3.5 denier (formerly 4 to 6 denier levels).

In step (B), the melt discharged yarn (4) of step (A) is quenched by passing through the cooling zone (3), if necessary, the distance from the nozzle 2 directly below the starting point of the cooling zone (3). That is, a short heating device can be installed in the hood length (L). This zone is called a delayed cooling zone or heating zone and may have a length of 140-220 mm and a temperature of 250-380 ° C. In the cooling zone 3, an open quenching method, a circular closed quenching method, a radial outflow quenching method, or the like may be applied according to a method of blowing cooling air. As such, by lowering the ambient temperature directly below the nozzle 2 to cool the temperature of the emitting yarn 4 as soon as possible, the solidification point of the spun polymer is increased and the radial tension is increased to increase the orientation of the undrawn yarn and the formation of tie chains. Subsequently, the quenched discharged yarn 4 may be oiled by the emulsion applying device 5 to 0.5 to 1.0% while passing through the cooling zone 3.

In step (C), the yarn is wound up at a spinning speed such that the birefringence of the undrawn yarn is 0.06 to 0.09 and the density is 1.360 to 1.375 in the first stretching roller 6, and the preferred spinning speed is 2500 to 2800 m / min. to be. If the birefringence is lower than 0.06, the tie chains are not sufficiently expressed during spinning, resulting in poor strength and dimensional stability during conversion to the treatment cord. If the birefringence is higher than 0.09, crystals are significantly produced during spinning, which lowers the post-stretchability, thereby lowering the yarn strength. Also, in terms of density, which is a comprehensive evaluation of molecular orientation and crystallization, similarly to birefringence, when the density is lower than 1.360, the strength and dimensional stability is lowered when switching to the treatment cord, and when the density is higher than 1.375, the yarn strength is lowered. Lowers.

In step (D), the yarn passing through the first stretching roller 6 is passed through a series of stretching rollers 7, 7, 8, 9 and 10 by spin draw, while 1.5 to 2.5, preferably 1.8. The final stretched yarn 11 is obtained by stretching at a total draw ratio of 2.3 to 2.3. As described above, the single yarn fineness of the final stretched yarn according to the present invention is 2.5 to 3.5 denier, when the single yarn fineness is less than 2.5 denier, the unevenness of the undrawn yarn is severe during spinning, resulting in a large number of filament cuts, resulting in stretching workability and yarn appearance. If it becomes poor, and exceeds 3.5 denier, the cooling rate will be slowed down and the freezing point will fall and the expression of a tie chain will become inadequate and the intensity | strength and dimensional stability at the time of switching to a processing cord will become low. At this time, according to a conventional method, the finished yarn can be heat set to a temperature of 190 to 240 ℃ (relaxing) to 2 to 5%.

Stretched polyester multifilament yarn prepared according to the method of the present invention, single yarn fineness of 2.5 to 3.5 denier, intrinsic viscosity of 0.94 to 1.00, DEG content of 0.65 to 0.9 wt%, CEG content of 23 wt% or less, 7.5 to 8.5 g strength of / d, elongation of 13.0 to 16.0%, shrinkage of 4.0 to 7.0%, and a silk factor of 27 or more (strength (g / d) x elongation at break (%)).

Further, according to the present invention, the drawn yarn can be converted into a treatment code by a conventional treatment method. For example, two cords of 1,500 denier yarns are plying and cabling at 390 turns / m (the number of twists based on typical polyester treated cords) to make cord yarns, which are then first dipping into a tank. in a tank) and then immersed in an adhesive solution (e.g. isocyanate + epoxy resin, or PCP (parachlorophenol) resin + RFL (resorcinol-formalin-latex)) and then at 130-160 ° C. in a drying zone. Dry for 150 to 200 seconds under 1.0 to 4.0% stretching, heat-set at 235 to 245 ° C. for 45 to 80 seconds under 2.0 to 6.0% stretching in a hot stretching zone, and then re-attach the adhesive liquid (eg RFL) Evaporation rate at 6.0-6.7% of E _2.25 (2.25 g / d) by immersion in water, followed by drying at 140-160 ° C. for 90-120 seconds and heat setting at 235-245 ° C. under -4.0-2.0% stretching for 45-80 seconds. ) And FS (free shrinkage) and treatment cords having strengths of 6.7 to 7.2 g / d can be prepared.

As such, the treatment cord formed from the high modulus and low shrinkage polyester multifilament yarn of the present invention is excellent in dimensional stability and strength and can be usefully used as a reinforcement material for rubber products such as tires and belts or for other industrial uses.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the present invention, but are not limited thereto. Various physical property evaluations of the yarns and treatment cords prepared in Examples and Comparative Examples of the present invention were performed by the following methods.

(1) Intrinsic viscosity (I.V.)

After dissolving 0.1 g of the sample in a reagent (90 ° C.) mixed with phenol and 1,1,2,3-tetrachloroethanol at a weight ratio of 6: 4 for 90 minutes to give a concentration of 0.4g / 100ml, Ubbelohde Transfer to a viscometer was carried out for 30 minutes in a 30 degreeC thermostat, and the drop number of seconds of the solution was calculated | required using a viscometer and an aspirator. The falling seconds of the solvent was also determined in the same manner, and then the R.V.value and the I.V.value were calculated by the following equations (1) and (2).

Where C represents the concentration of the sample in solution (g / 100ml).

(2) CEG content

In accordance with ASTM D 664 and D 4094, 0.2 g of the sample was weighed and placed in a 50 ml Erlenmeyer flask, 20 ml of benzyl alcohol was added and heated to 180 ° C. using a hot plate for 5 minutes. After dissolving, forced cooling to 160 ° C., 5-6 drops of phenolphthalene at 135 ° C., titrated with 0.02N KOH, and the CEG content (COOH million equiv) according to the following equation 3 at a point where colorless to pink was changed. / Kg of sample) was calculated.

Where A is the amount of KOH consumed in the titration of the sample (ml), B is the amount of KOH consumed in the titration of the blank sample (ml), and W is the weight of the sample (g).

(3) DEG content

1 g of the sample was weighed and placed in a 50 ml container. Then, 3 ml of monoethanolamine was added and heated using a hot plate to completely dissolve the sample. Then, the sample was cooled to 100 ° C. and 0.005 g of 1,6-hexanediol was dissolved in 20 ml of methanol. The solution was added and neutralized by adding 10 g of terephthalic acid. The obtained neutralized solution was filtered using a funnel and filter paper, and then the filtrate was subjected to gas chromatography (Gas Chromatography) to determine the DEG content (wt%). GC analysis was performed using a Shimadzu GC analyzer using a Shimazu GC manual. Followed.

(4) strength

Using Instron 5565 (Instron, USA), 250 mm sample length, 300 mm / min tensile speed and 80 turns / s under standard conditions (20 ° C., 65% relative humidity) according to ASTM D 885. Elongation was measured under conditions of m.

(5) density and crystallinity

The density (ρ) of the sample was obtained using a xylene / carbon tetrachloride density gradient tube at a temperature of 23 ° C., and the crystallinity (%) was calculated as in Equation 4 below. At this time, the density gradient pipe has a density in the range of 1.34 ~ 1.41 g / cm ² and was prepared according to the provisions of ASTM D 1505.

Where p represents the density (g / cm 3) of the sample and p and c represent 1.455 and 1.335 g / cm 3 as the density of the crystal and amorphous, respectively.

(6) birefringence

The birefringence was measured using a polarizing microscope equipped with a Berek compensator.

(7) crystal orientation function (fc)

After fixing the sample to a holder (fiber) attached to the fiber specimen to a certain thickness (about 0.5mm), and then fixed the fiber axis of the sample to be perpendicular to the ground. Next, the counter is fixed at the peak position of the (010) plane measured by 2θ-scan according to the X-ray diffraction method (voltage: 35KV, current: 20mA), and a 360 ° azimuthal scan The total width at half maximum (FWHM) was measured at the maximum value / 2, and the crystal orientation function (fc) was obtained as shown in Equation 5 below.

(8) amorphous orientation function (fa)

According to Equation 6 below, a non-orientation orientation function fa was obtained.

Wherein Δn represents birefringence, fc represents a crystal orientation function, Xc represents crystallinity, and Δnc and Δna represent 0.220 and 0.275 as intrinsic birefringences of the crystal and amorphous, respectively.

(9) shrinkage

The sample was left at 20 ° C. and 65% relative humidity for at least 24 hours, and then weighed at a weight equivalent to 0.1 g / d to measure the length (L ₀ ). After the treatment for a minute and left out for 4 hours or more, the load (L) was measured and the shrinkage was calculated by the following equation (7).

(10) Intermediate Shinto

On the S-S curve, the yarn was elongated at 4.5 g / d and the treated cord was elongated at 2.25 g / d.

(11) Dimensional stability

The dimensional stability (%) of the treatment cord is defined as the high modulus at a given shrinkage as properties related to tire sidewall indentation (SWI) and handling, E _2.25 (elongation at _2.25 g / d) + FS Free Shrinkage is useful as a measure of dimensional stability for treatment codes that have undergone different heat treatments, and the lower the better the dimensional stability.

Example 1

An antimony compound was added as a polymerization catalyst so that the residual amount of antimony metal in the polymer was 220 ppm, thereby preparing a solid-state polymerized polyethylene terephthalate chip having an intrinsic viscosity (I.V.) of 1.1 and a water content of 20 ppm. The produced chip was melt spun using an extruder at a discharge amount of 900 g / min and a temperature of 288 ° C. such that the single yarn fineness of the final stretched yarn was 3.0 denier. The discharge yarn is then solidified by passing a 130 mm non-heating hood (delay cooling zone) directly below the nozzle and a 530 mm length cooling zone (20 ° C., cooling air blowing with a wind speed of 0.5 m / sec), followed by oiling with spinning oil. It was then wound up at a spinning speed of 2600 m / min to make an undrawn yarn. Subsequently, the undrawn yarn was subjected to three-stage drawing with a total drawing ratio of 2.15, heat-set at a temperature of 230 ° C., relaxed by 2%, and wound to prepare a final drawn yarn (yarn) of 1500 denier.

After two strands of yarn were rolled up and down at 390 turns / m to prepare cord yarns, the cord yarns were immersed in the adhesive solution of (PCP resin + RFL) in a dipping tank and then stretched at 150 ° C. under 2% stretching in a dry area. Dry for 150 seconds, heat set at 60 ° C. under 8% elongation at 240 ° C. for 60 seconds, then again immerse in RFL, dry 100 seconds at 240 ° C. and heat set at 240 ° C. for 60 seconds under -4% elongation, Prepared.

The physical properties of the drawn yarn and the treatment cord thus prepared are shown in Table 1 below.

Examples 2-7 and Comparative Examples 1-7

The experiment was carried out in the same manner as in Example 1 while varying the intrinsic viscosity, spinning temperature, spinning speed, single yarn fineness, non-drawn yarn orientation (birefringence or density) or total draw ratio as shown in Table 1 below. Gentleman and treatment cords were prepared.

The physical properties of the drawn yarn and the treatment cord thus prepared are shown in Table 1 below.

Polyester multifilament yarns according to the present invention have improved properties including high modulus and low shrinkage, and the treatment cords formed from these yarns have excellent dimensional stability and strength and are used as reinforcements for rubber products such as tires and belts or for other industrial uses. It can be usefully used as.

Claims (4)

(A) obtaining a discharge yarn by melt spinning a solid-phase polymerized polyester chip containing at least 90 mol% of ethylene terephthalate units and having an intrinsic viscosity in the range of 1.05 to 1.13 at a temperature of 290 to 298 ° C., (B) quenching the molten yarn through a cooling zone; (C) winding the yarn at a spinning speed such that the birefringence of the undrawn yarn is 0.06 to 0.09 and the density is 1.360 to 1.375, and (D) a polyester multifilament yarn having the following physical properties, prepared by a method comprising hot stretching a wound yarn at a total draw ratio of 1.5 to 2.5: (1) single thread fineness of 2.5 to 3.5 denier, (2) intrinsic viscosity of 0.94 to 1.00, (3) DEG (diethylene glycol) content of 0.65 to 0.9 wt%, (4) 23 wt% or less of CEG (carboxyl) Endgroup) content, (5) strength of 7.5 to 8.5 g / d, (6) elongation of 13.0 to 16.0%, (7) shrinkage of 4.0 to 7.0%, and (8) silk factor of at least 27 (strength (g / d) x √ Elongation at break (%)). The method of claim 1, Polyester multifilament yarn produced by the process, characterized in that the winding up at a speed of 2500 to 2800 m / min in step (C). A treatment code having the following physical properties obtained by vertically stretching two strands of the polyester multifilament yarn of claim 1 and treating resorcinol-formalin-latex (RFL): (a) E _2.25 (extension at _2.25 g / d) + FS (free shrinkage) of 6.0 to 6.7%, and (b) strength of 6.7 to 7.2 g / d. A rubber product in which the treatment cord of claim 3 is incorporated as a reinforcing material.